Written by James Cooper
Last Updated

It’s important to know when you should wait after eating before running. This article will provide some insight into this topic, which is affected by many different factors.

When you eat a meal, your body starts breaking down food into smaller units as energy. This process is called digestion. During digestion, the entire body slows down and only focuses on this activity. Because of this, you should not exercise right after eating a large meal because there will be less blood flow going to your muscles and more going to your stomach to aid digestion.

When you eat a meal, the digestive process begins by breaking down large food molecules into smaller ones. This is called Assimilation. The small pieces are then transferred across the intestinal membrane and into the bloodstream for distribution to other locations in the body (this is called distribution).

Finally, the small pieces are put together into body parts to create new molecules that your cells can use for energy (Resynthesis). The digestive process requires a lot of blood flow, which means less blood will be available for exercising muscles.

Types of Food

The type of food eaten affects digestion time and, therefore, should affect when you choose to run.

Carbohydrates are broken down into sugars very quickly and can cause an immediate spike in blood sugar levels, known as Glycemic Index (GI). High GI foods like sugary snacks and soft drinks will break down more quickly than low GI foods such as whole-wheat bread and pasta.

Proteins and fats take longer to break down and cause a slower and more sustained release of blood sugar; this is known as Glycemic Load (GL). Other factors like how much fat is in the food will affect GL. Foods that contain a lot of fat or protein will generally have a lower glycemic index. For example, ice cream has a high GI, but because of the fat content of the milk used, it has a low GL.

While digesting food, your body mainly focuses on this process which means less blood flow will get to your muscles.

Like the type of food, the exercise duration can affect digestion time and therefore should affect when you choose to run.

The longer you exercise, the more your body will be focusing on exercising muscles instead of digestion which means more blood flow will get to your stomach for digestion.

The Intensity of the Workout

The intensity of the workout also affects blood flow distribution. For example, during high-intensity training, there is less blood flow going towards digestion because the body will try to deliver nutrients and remove waste products. On the other hand, during a low-intensity workout, there is more blood flow going towards digestion because less energy is being used by exercising muscles.

The duration of your exercise affects whether you should wait before eating after working out.

Research in the Journal of the International Society of Sports Nutrition found that it takes at least 45 minutes for your body to go from a fed state to a fasting state when exercising, so you should wait for at least this long after finishing before eating.

Age

Age may also affect digestion time and, therefore, should affect when you choose to run.

As we get older, we tend to have a slower digestive system because we produce less stomach acid, and our organs seem to work slower.

Gender

Gender may also affect digestion time and, therefore, should affect when you choose to run:

Female athletes often report feeling better after eating during exercise than waiting until it’s all done. The reason for this is that females generally have a slower digestion time than males.

Final Thoughts

Because the time it takes for your body to go from a fed state to a fasting state can vary between 45 minutes and an hour, it is recommended that you should only eat after exercising if you are doing less than an hour of exercise. If working out for more than an hour, it is recommended that you wait at least 45 minutes before eating after finishing your workout.

Other factors to consider are the intensity of your training, food type eaten, and age. Remember, many different factors can affect when you should eat after exercising! However, the most important thing is to find what works best for you!


Sources:

http://www.mayoclinic.org/healthy-lifestyle/exercise/in-depth/exercise-and-food/art-20044834
http://www.livestrong.com/article/467175-how-long-to-wait-after-eating-to-run/#tabs

“Exercise and Food Intake: The Role of Glycemic Index.” Journal of the International Society of Sports Nutrition 5 (2008):17. Academic Search Premier. Web. 5 Jan 2013.

“Effects of Exercise Intensity and Duration on the Post-Exercise Anaerobic Response.” Journal of Science and Medicine in Sport / Sports Medicine Australia ( 1997):110–14. Academic Search Premier. Web. 5 Jan 2013.

“Gender Differences In Carbohydrate Metabolism During Prolonged, Submaximal Exercise.” Journal of Applied Physiology ( 2000):1944-51. Academic Search Premier. Web. 5 Jan 2013.

“Identification Of The Glycemic Index For Ten Popular Australian Foods.” Asia Pacific Journal of Clinical Nutrition 17 (2008):151-6. Academic Search Premier. Web. 5 Jan 2013.

“Exercise And The Digestive System.” Medical Sciences Bulletin 18 (2002):1-5. Academic Search Premier. Web. 5 Jan 2013.

Social Share